Change-speed lever for a bicycle gear

ABSTRACT

A shift mechanism for a bicycle gear assembly that includes an actuating part that may be moved by an actuating lever or a release lever to shift between the gears of the gear assembly. The actuating and release levers operate independently from each other. The actuating part has a winding groove for receiving a cable connected to the gear assembly and first and second toothed segments. The release lever controls a detent element having first and second detent noses that are alternately engageable with the first and second toothed segments, respectively. The release lever may also have a cam contour that allows at least two gears to be shifted upon actuation of the release lever.

BACKGROUND OF THE INVENTION

The invention relates to a shift mechanism for a bicycle gear assemblyand in particular a shift mechanism that includes an actuating lever anda release lever that operate independently from each other to shiftbetween the gears.

EP 0 352 733 B1 discloses a shift mechanism for a bicycle gear assemblythat is a trigger shift mechanism, in which the tension cable can bewound up against the spring of the bicycle gear and released by a detentmechanism through the actuation of a single lever. This is achieved byan actuating lever rotatably mounted about a central axis to tension thetension cable. One detent device is traversed per shift step. A releaselever is actuated to cause the actuating lever to be pulled back by thetension cable into the next detent stage for the next gear ratio. Therelease lever is an integral part of the actuating lever. The releaselever being operated in a plane perpendicular to the plane of operationof the actuating lever. The pivot for the release lever is integratedinto the actuating lever and, as the individual gear ratios areselected, corotates about the central axis of the actuating lever. Adrawback associated with this configuration is that in the extremepositions of the shift mechanism, between the hill-climbing gears andthe speed gears, the actuating lever is located in an area which isergonomically unfavorable.

French Patent FR 2 701 917 (93 02255) discloses a release lever and anactuating lever that are arranged in two parallel planes of action. Thisconfiguration allows an actuating part to be turned by the actuatinglever about a common central axis, while the release lever resets thepart, gear ratio by gear ratio by means of a toothed rocker bar. Themanner in which the rocker bar engages the toothing on the actuatingpart is similar to a toothed rocker bar in a mechanical clock, which isactuated by a balance.

SUMMARY OF THE INVENTION

This invention combines the features of EP 352 733 with the features ofFR 2 701 917 inasmuch as a release lever engages a first toothed segmentand a release lever acts on a second toothed segment. The release leverand an actuating lever acting in planes that are parallel to oneanother. The two toothed segments are connected by a detent elementdesigned as a rocker and having detent noses that can alternately engagein one set of toothing of the toothed segments or the other. The detentelement is controlled by the release lever. The release lever has a camcontour connected to the detent element by means of an extension. Thedetent element engages repeatedly and alternately the toothing of thetwo toothed segments when the release lever is actuated in onedirection. The detent element is spring-loaded toward the toothedsegment on the actuating lever and thus the detent element is in itsrest position when it is engaged with this toothed segment. When thefirst toothed segment is turned by the actuating lever, the detentelement slides over the toothed segment, and the extension of the detentelement is released from the cam contour of the release lever withoutperforming an action.

A tension cable, which is wound up by the rotation of the toothedsegment by means of the actuating lever, changes gear ratios in thebicycle gear and simultaneously tensions the cable against a spring inthe bicycle gear. This tensioning can take place from the first to thelast gear ratio. The release lever relaxes the cable and the toothedsegments are moved back tooth by tooth, gear ratio by gear ratio. Duringthis process, the release lever's cam contour, which comprises a risingcam part and a falling cam part, first moves the detent element into aposition of engagement and then out of a position of engagement with thetoothed segment. If the release lever is released, the extension on thedetent element moves backward over the cam contour and a second gearchange is performed. The cam contour may be extended to provide aplurality of rising and falling cam parts. This means that a pluralityof gears can be shifted in a forward movement of the release lever, anequal number of gear change operations being added during the return ofthe release lever. Since the actuating lever is connected to the firsttoothed segment by a pawl, the actuating part is moved by the actuationof the release lever, this movement by the pawl being decoupled from theactuating lever.

It is therefore the object of the invention to create a shift mechanismfor actuating a bicycle gear assembly which is designed as a triggershift mechanism and can actuate a cable to shift one or more gear ratiosnot just in a direction of rotation corresponding to the winding up ofthe cable but can also shift via at least one but also via a pluralityof gear ratios in a direction of rotation corresponding to the unwindingof the cable through the release of the cable.

BRIEF DESCRIPTION OF THE DRAWINGS

The solution is described in the characterizing part of the main claimand in the subclaims. A shift mechanism having the features described inthe statement of the object will be explained with reference to a numberof drawings, in which:

FIG. 1 shows a shift mechanism for a bicycle, having a housing, anactuating lever and a release lever, and a detent element actuated bythe release lever;

FIG. 2 shows the shift mechanism, having an actuating part and twotoothed segments, into which the detent element actuated by the releaselever engages;

FIG. 3 shows the release lever with a cam contour for the actuation ofthe detent element;

FIG. 4 shows the cam contour in the release lever with a plurality ofrising and falling cam parts; and

FIG. 5 shows the actuating lever with a pawl that can be operated on thehousing side and is intended to interact with toothing on a seconddetent disk.

DETAILED DESCRIPTION OF THE INVENTION

The invention describes a bicycle gear shift mechanism that can bearranged on bicycle handlebars and controls a bicycle gear assembly.According to FIG. 1, the shift mechanism includes a housing 2 with anactuating part 3 that can be moved by an actuating lever 1 and by arelease lever 10. The actuating part 3 has a winding groove 4 for atension cable 5, which is connected to the bicycle gear assembly and iskept under tension by a spring located there. The actuating part 3 has afirst detent disk 16 with a first toothed segment 8 and a second detentdisk 17 with a second toothed segment 9. The actuating part 3 having aconfiguration such that it can rotate about a central axis 11 with thefirst detent disk 16 and the second detent disk 17. The actuating part 3can be turned by the actuating lever 1 by means of a pawl 6, whichengages in toothing 7 connected rotationally to the actuating part 3.When the actuating lever 1 is moved, this movement is transmitted to theactuating part 3 by the pawl 6, resulting in the cable 5 being woundonto the winding groove 4, and thereby tensioning the spring andchanging gear ratios in the bicycle gear assembly.

FIG. 2 shows a play-free trigger device in the form of a detent element12 having a first detent nose 13 and a second detent nose 14. The detentelement 12 is arranged pivotably on a pivot 15 fixed in relation to thehousing. The first detent nose 13 engages the first toothed segment 8and the second detent nose 14 engages the second toothed segment 9alternatively. The detent element 12 is supported against the housing bya spring 23 and interacts by means of the second detent nose 14 with thesecond toothed segment 9 of the second detent disk 17 in the state ofrest, thereby ensuring that, once a gear ratio has been selected in thebicycle gear assembly, it is retained. The detent element 12 has anextension 20 that interacts with a cam contour 19 in the release lever10. The extension 20 is held in continuous contact with an edge 18 bythe spring 23 and, when the release lever 10 is actuated, the extension20 slides on the cam contour 19, resulting in the detent element 12performing a rocking motion causing the second detent nose 14 and thefirst detent nose 13 to alternately engage the second toothed segment 9and the first toothed segment 8, respectively.

Referring to FIGS. 3 and 4, the cam contour 19 has at least one risingcam part 21 and one falling cam part 22, along which the extension 20must slide. To release the cable 5 to shift between gear ratios, therelease lever 10 is actuated to disengage the retaining connectionbetween the second detent nose 14 and the second toothed segment 9,resulting in the actuating part being turned by the cable in the windinggrove 4 which is being pulled back gear ratio by gear ratio by thespring situated on the bicycle gear. In this case, the extension 20 ofthe detent element 12 runs up onto the rising cam part 21 of the camcontour 19, the release lever 10 has turned through a partial angle Wand the first detent nose 13 has entered into engagement with the firsttoothed segment 8. When the cable 5 has been released from the windinggroove 4 by about half a gear ratio; the second half of the gear ratiois traversed by virtue of the fact that, in accordance with FIG. 3, theextension moves back on the falling cam part 22 into its originalposition, provided that the release lever 10 is turned by a furtherpartial angle W.

In trigger shift mechanisms, all the levers return to their startingposition through spring force once shifting of the gear ratios in thebicycle gear has been completed, which means that the release lever 10shown in FIG. 3 can shift a maximum of two gear ratios with its camcontour 19 in the direction of rotation corresponding to the unwindingof the cable. If only one gear ratio is to be shifted, it is sufficientto turn the release lever 10 merely through a partial angle W until theextension 20 has reached the end of the rising cam part. If the releaselever 10 is then released, it returns to its starting position, and theextension 20 returns to its original position. Since, in accordance withFIG. 4, the cam contour 19 has four partial angles W, i.e. two risingcam parts 21 and two falling cam parts 22, it is possible to shift amaximum of 4 gears if the release lever 10 is turned until the extension20 has traversed all cam parts 21 and 22 in both directions. To make iteasier to shift the gear ratios in the bicycle gear assembly, a detentcan be built into the release lever 10, making it easier for the riderto find the individual end points for the travel of the release lever 10for the planned gear ratios.

FIG. 5 shows an actuating lever 1, which, in the position indicated,occupies a rest position N as long as the first and last gear ratios ofthe bicycle gear are not selected. Arranged on the second detent disk 17or actuating part 3 is a stop extension 27, which interacts with a firststop 25 and a second stop 26 on the actuating lever 1 when the firstgear ratio or last gear ratio is selected in the bicycle gear. Assumingthat the first gear ratio is selected when the stop extension 27 hasbeen turned into the outermost position counter to the direction ofrotation, the first stop 26 is designed such that the actuating lever 1can no longer return to its rest position N and remains in a restposition I of the first gear ratio. Such a measure indicates to therider by feel that all the gear ratios have been traversed and that thefirst gear ratio has been reached. It should likewise be communicated tothe rider by feel that shifting further would be pointless through arest position II of the last gear ratio. This is achieved by virtue ofthe fact that the stop extension 27 runs clockwise against the firststop 25, thereby preventing the actuating lever 1 from returning to therest position N.

The advantage of the present invention is that it is possible to shiftthrough the gear ratios of the bicycle gears both with the actuatinglever 1 and with the release lever 10. The detent element 12 of bothlevers 1 and 10 being decoupled such that the movements of one lever 1or 10 are not transmitted to the other lever 1 or 10 while the triggerprinciple, namely the ability to select individual gear ratios, ismaintained and both levers 1, 10 always return to their respectiveinitial positions. The present invention also allows the first and thelast gear ratios to occupy rest positions I and II that are differentfrom the normal rest position N in order to indicate the end points ofthe shift steps to the rider by feel without the need to make visualcontact with a gear display.

What is claimed is:
 1. A shift mechanism for a bicycle gear assembly,comprising: a housing having an axis; an actuating lever rotatable aboutthe axis; an actuating part rotatable about the axis and having awinding groove for receiving a tension cable, the actuating part havinga toothing; a pawl engageable with the toothing on the actuating part towind up the tension cable; first and second toothed segments connectedto the actuating part; a detent element having a first detent nose and asecond detent nose, the first detent nose engageable with the firsttoothed segment and the second detent nose engageable with the secondtoothed segment such that when one of the first and second detent nosesis disengaged from the toothed segment, the actuating part is turned bytensile force of the tension cable; and a release lever operativelyconnected to the detent element for controlling the detent element. 2.The shift mechanism as claimed in claim 1, wherein the detent element ispivotably mounted on a pivot fixed in relation to the housing andsubstantially perpendicular to the axis.
 3. The shift mechanism asclaimed in claim 2, wherein the pivot is located a distance from theaxis that substantially equals radii of the first and second toothedsegments.
 4. The shift mechanism as claimed in claim 2, wherein thepivot is approximately centrally located between the first toothedsegment and the second toothed segment.
 5. The shift mechanism asclaimed in claim 1, wherein the detent element is spring-loaded relativeto the housing toward engagement with the second toothed segment.
 6. Theshift mechanism as claimed in claim 1, wherein the first toothed segmentis rotationally connected to the actuating part by a first detent disk,and the second toothed segment is rotationally connected to theactuating part by a second detent risk.
 7. A shift mechanism for abicycle gear assembly, comprising: a housing having an axis; anactuating lever rotatable about the axis; an actuating part disposed inthe housing and rotatable about the axis, the actuating part havingtoothing and a winding groove for receiving a tension cable; a pawlengageable with toothing on the actuating part to wind up the tensioncable; first and second toothed segments are connected to the actuatingpart; a detent element engageable with the first and second toothedsegment; and a release lever operatively connected to the detentelement, the release lever having a cam contour having at least onerising cam part and one falling cam part to allow at least two gearratios to be shifted upon actuating the release lever, while the detentelement engages the cam contour.
 8. The shift mechanism as claimed inclaim 7, wherein the detent element includes a first detent noseengageable with the first toothed segment and a second detent noseengageable with the second toothed segment, and engages the releaselever such that, when the release lever is actuated, the detent elementperforms a rocking motion, during which, in succession, a first detentnose, on the one hand, comes into engagement with the first toothedsegment, and a second detent nose, on the other hand, comes intoengagement with the second toothed segment.
 9. The shift mechanism asclaimed in claim 7, wherein the detent element has an edge that engagesthe cam contour on the release lever.
 10. The shift mechanism as claimedin claim 9, wherein the edge is part of an extension on the detentelement.
 11. The shift mechanism as claimed in claim 7, wherein therelease lever is designed as a trigger lever that returns to a restposition (N) through the restoring force of a spring after eachactuation.
 12. The shift mechanism as claimed in claim 1, wherein thepawl is pivotably mounted on the actuating lever for engaging thetoothing connected to the actuating part.
 13. The shift mechanism asclaimed in claim 12, wherein the first toothed segment is rotationallyconnected to the actuating part by a first detent disk, and the secondtoothed segment is rotationally connected to the actuating part by asecond detent disk and the toothing is connected to one of the first andsecond detent disks.
 14. The shift mechanism as claimed in claim 13,wherein the toothing is integrally connected to the second detent disk.15. The shift mechanism as claimed in claim 12, wherein the pawl is outof engagement with the toothing in the rest position of the actuatinglever.
 16. A shift mechanism for a bicycle gear assembly, comprising: ahousing having an axis; an actuating lever rotatable about the axis; anactuating part rotatable about the axis, the actuating part havingtoothing and a winding groove for receiving a tension cable, theactuating lever controlling the actuating part; a pawl engageable withtoothing on the actuating part to wind up the tension cable; first andsecond toothed segments connected to the actuating part; and a releaselever alternately engageable with the first toothed segment and thesecond toothed segment, the actuating lever having, relative to theactuating part, at least one stop engageable with a stop extension whena first or a last gear ratio is reached, thereby distinguishing the restposition (I) of the actuating lever in the first gear ratio and/or therest position (II) of the actuating lever in the last gear ratio fromthe normal rest position (N) of the actuating lever in the remaininggear ratios.